Electrode catalyst for fuel cells

Abstract

An electrode catalyst for fuel cells that can inhibit an increase in gas diffusion resistance includes a carbon material having a ratio of a peak intensity IA derived from an amorphous structure to a peak intensity IG derived from a graphite structure in an X-ray diffraction spectrum (ratio IA/IG) of 0.90 or less as a catalyst-supporting carrier.

What is claimed is: 
     
       1. An electrode catalyst for fuel cells, comprising:
 a carbon material having:
 a ratio of a peak intensity I A  derived from an amorphous structure to a peak intensity I G  derived from a graphite structure in an X-ray diffraction spectrum (ratio I A /I G ) of 0.90 or less, and 
 a ratio of a D-band peak intensity to a G-band peak intensity in a Raman spectrum (ratio D/G) of 1.50 or more; and 
 
 a catalyst metal supported by the carbon material. 
 
     
     
       2. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio I A /I G  of the carbon material is 0.80 or less. 
     
     
       3. The electrode catalyst for fuel cells according to  claim 1 , wherein the catalyst metal comprises platinum or a platinum alloy. 
     
     
       4. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio D/G of the carbon material is in the range of from 1.54 to 1.90. 
     
     
       5. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio D/G of the carbon material is in the range of from 1.60 to 1.68. 
     
     
       6. The electrode catalyst for fuel cells according to  claim 1 , wherein a crystallite thickness Lc of the (002) plane of the carbon material is in the range of from 1.0 nm to 3.0 nm. 
     
     
       7. The electrode catalyst for fuel cells according to  claim 1 , wherein a crystal width La of the carbon material is in the range of from 1.8 nm to 3.2 nm. 
     
     
       8. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio I A /I G  of the carbon material is in the range of from 0.47 to 0.90. 
     
     
       9. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio I A /I G  of the carbon material is in the range of from 0.47 to 0.80. 
     
     
       10. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio I A /I G  of the carbon material is in the range of from 0.47 to 0.70. 
     
     
       11. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio I A /I G  of the carbon material is in the range of from 0.47 to 0.60. 
     
     
       12. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio D/G of the carbon material is in the range of from 1.50 to 1.68. 
     
     
       13. The electrode catalyst for fuel cells according to  claim 1 , wherein the peak intensity ratio D/G of the carbon material is in the range of from 1.60 to 1.90. 
     
     
       14. The electrode catalyst for fuel cells according to  claim 1 , wherein the carbon material has a specific surface area of 400 m 2 /g or more. 
     
     
       15. The electrode catalyst for fuel cells according to  claim 1 , wherein the carbon material has a specific surface area in the range of from 400 to 1400 m 2 /g. 
     
     
       16. The electrode catalyst for fuel cells according to  claim 1 , wherein the carbon material has an average particle size in the range of from 0.05 μm to 10 μm. 
     
     
       17. A catalyst layer for fuel cells, comprising the electrode catalyst for fuel cells according to  claim 1 . 
     
     
       18. The catalyst layer for fuel cells according to  claim 17  further comprising an ionomer. 
     
     
       19. A fuel cell comprising the electrode catalyst for fuel cells according to  claim 1 . 
     
     
       20. A fuel cell comprising the catalyst layer for fuel cells according to  claim 17 .